Multimedia transmission is widespread in a recent network environment. Especially, video images occupy a large bandwidth in multimedia communication. In this context, compression techniques aiming at higher transmission rates and better video quality have been proposed.
One of video compression standards is H.264/AVC (MPEG-4 Advanced Video Coding). Like conventional coding techniques such as MPEG-1, MPEG-2, and MPEG-4, H.264/AVC was designed to achieve high-efficiency coding using intra-coding mode and inter-coding mode.
The intra-coding mode relies on the fact that there is a high spatial correlation within one video frame. After prediction data of a current image block to be encoded is generated using adjacent image blocks, spatial redundancy is eliminated from the predicted data in the intra-coding mode. On the other hand, the inter-coding mode relies on the fact that there is a high temporal correlation between images. In the inter-coding mode, prediction data of a current image is generated using images previous to or next to the current image and then temporal redundancy is eliminated from the prediction data. In general, accurate prediction data is generated using an interpolation filter before a prediction block is searched for, in the inter-coding method.
Conventionally, however, interpolation is repeated using only a preset single interpolation filter with no regard to the characteristics of an input image. As a consequence, the conventional interpolation technology is not effective in generating various accurate prediction data, that is, in interpolating an input image in an optimal manner in a recent multimedia communication environment having a variety of images. Another shortcoming with the conventional interpolation technology is high computation complexity in relation to processing high-quality, large-capacity images.
Accordingly, there exists a pressing need for an interpolation scheme having reduced computation complexity, for encoding high-quality, large-capacity images, especially a more accurate interpolation scheme for an input image containing various pieces of video information.